The relationship between the morphology and kinematics of galaxies and its dependence on dark matter halo structure in EAGLE

Adrien C. R. Thob, Robert A. Crain, Ian G. McCarthy, Matthieu Schaller, Claudia D. P. Lagos, Joop Schaye, Geert Jan J. Talens, Philip A. James, Tom Theuns, Richard G. Bower

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We investigate the connection between the morphology and internal kinematics of the stellar component of central galaxies with mass M-star > 10(9.5) M-circle dot in the EAGLE simulations. We compare several kinematic diagnostics commonly used to describe simulated galaxies, and find good consistency between them. We model the structure of galaxies as ellipsoids and quantify their morphology via the ratios of their principal axes. We show that the differentiation of blue star-forming and red quiescent galaxies using morphological diagnostics can be achieved with similar efficacy to the use of kinematical diagnostics, but only if one is able to measure both the flattening and the triaxiality of the galaxy. Flattened oblate galaxies exhibit greater rotational support than their spheroidal counterparts, but there is significant scatter in the relationship between morphological and kinematical diagnostics, such that kinematically similar galaxies can exhibit a broad range of morphologies. The scatter in the relationship between the flattening and the ratio of the rotation and dispersion velocities (upsilon/sigma) correlates strongly with the anisotropy of the stellar velocity dispersion: at fixed upsilon/sigma, flatter galaxies exhibit greater dispersion in the plane defined by the intermediate and major axes than along the minor axis, indicating that the morphology of simulated galaxies is influenced significantly by the structure of their velocity dispersion. The simulations reveal that this anisotropy correlates with the intrinsic morphology of the galaxy's inner darkmatter halo, i.e. the halo's morphology that emerges in the absence of dissipative baryonic physics. This implies the existence of a causal relationship between the morphologies of galaxies and that of their host dark matter haloes.

Original languageEnglish
Pages (from-to)972-987
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume485
Issue number1
DOIs
Publication statusPublished - May 2019

Cite this

Thob, Adrien C. R. ; Crain, Robert A. ; McCarthy, Ian G. ; Schaller, Matthieu ; Lagos, Claudia D. P. ; Schaye, Joop ; Talens, Geert Jan J. ; James, Philip A. ; Theuns, Tom ; Bower, Richard G. / The relationship between the morphology and kinematics of galaxies and its dependence on dark matter halo structure in EAGLE. In: Monthly Notices of the Royal Astronomical Society. 2019 ; Vol. 485, No. 1. pp. 972-987.
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abstract = "We investigate the connection between the morphology and internal kinematics of the stellar component of central galaxies with mass M-star > 10(9.5) M-circle dot in the EAGLE simulations. We compare several kinematic diagnostics commonly used to describe simulated galaxies, and find good consistency between them. We model the structure of galaxies as ellipsoids and quantify their morphology via the ratios of their principal axes. We show that the differentiation of blue star-forming and red quiescent galaxies using morphological diagnostics can be achieved with similar efficacy to the use of kinematical diagnostics, but only if one is able to measure both the flattening and the triaxiality of the galaxy. Flattened oblate galaxies exhibit greater rotational support than their spheroidal counterparts, but there is significant scatter in the relationship between morphological and kinematical diagnostics, such that kinematically similar galaxies can exhibit a broad range of morphologies. The scatter in the relationship between the flattening and the ratio of the rotation and dispersion velocities (upsilon/sigma) correlates strongly with the anisotropy of the stellar velocity dispersion: at fixed upsilon/sigma, flatter galaxies exhibit greater dispersion in the plane defined by the intermediate and major axes than along the minor axis, indicating that the morphology of simulated galaxies is influenced significantly by the structure of their velocity dispersion. The simulations reveal that this anisotropy correlates with the intrinsic morphology of the galaxy's inner darkmatter halo, i.e. the halo's morphology that emerges in the absence of dissipative baryonic physics. This implies the existence of a causal relationship between the morphologies of galaxies and that of their host dark matter haloes.",
keywords = "galaxies: evolution, galaxies: formation, galaxies: haloes, galaxies: kinematics and dynamics, galaxies: structure, ANGULAR-MOMENTUM EVOLUTION, STAR-FORMATION, INTRINSIC ALIGNMENTS, SAURON PROJECT, STELLAR MASS, BLACK-HOLES, DISC GALAXY, SIMULATIONS, FEEDBACK, SHAPES",
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The relationship between the morphology and kinematics of galaxies and its dependence on dark matter halo structure in EAGLE. / Thob, Adrien C. R.; Crain, Robert A.; McCarthy, Ian G.; Schaller, Matthieu; Lagos, Claudia D. P.; Schaye, Joop; Talens, Geert Jan J.; James, Philip A.; Theuns, Tom; Bower, Richard G.

In: Monthly Notices of the Royal Astronomical Society, Vol. 485, No. 1, 05.2019, p. 972-987.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The relationship between the morphology and kinematics of galaxies and its dependence on dark matter halo structure in EAGLE

AU - Thob, Adrien C. R.

AU - Crain, Robert A.

AU - McCarthy, Ian G.

AU - Schaller, Matthieu

AU - Lagos, Claudia D. P.

AU - Schaye, Joop

AU - Talens, Geert Jan J.

AU - James, Philip A.

AU - Theuns, Tom

AU - Bower, Richard G.

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N2 - We investigate the connection between the morphology and internal kinematics of the stellar component of central galaxies with mass M-star > 10(9.5) M-circle dot in the EAGLE simulations. We compare several kinematic diagnostics commonly used to describe simulated galaxies, and find good consistency between them. We model the structure of galaxies as ellipsoids and quantify their morphology via the ratios of their principal axes. We show that the differentiation of blue star-forming and red quiescent galaxies using morphological diagnostics can be achieved with similar efficacy to the use of kinematical diagnostics, but only if one is able to measure both the flattening and the triaxiality of the galaxy. Flattened oblate galaxies exhibit greater rotational support than their spheroidal counterparts, but there is significant scatter in the relationship between morphological and kinematical diagnostics, such that kinematically similar galaxies can exhibit a broad range of morphologies. The scatter in the relationship between the flattening and the ratio of the rotation and dispersion velocities (upsilon/sigma) correlates strongly with the anisotropy of the stellar velocity dispersion: at fixed upsilon/sigma, flatter galaxies exhibit greater dispersion in the plane defined by the intermediate and major axes than along the minor axis, indicating that the morphology of simulated galaxies is influenced significantly by the structure of their velocity dispersion. The simulations reveal that this anisotropy correlates with the intrinsic morphology of the galaxy's inner darkmatter halo, i.e. the halo's morphology that emerges in the absence of dissipative baryonic physics. This implies the existence of a causal relationship between the morphologies of galaxies and that of their host dark matter haloes.

AB - We investigate the connection between the morphology and internal kinematics of the stellar component of central galaxies with mass M-star > 10(9.5) M-circle dot in the EAGLE simulations. We compare several kinematic diagnostics commonly used to describe simulated galaxies, and find good consistency between them. We model the structure of galaxies as ellipsoids and quantify their morphology via the ratios of their principal axes. We show that the differentiation of blue star-forming and red quiescent galaxies using morphological diagnostics can be achieved with similar efficacy to the use of kinematical diagnostics, but only if one is able to measure both the flattening and the triaxiality of the galaxy. Flattened oblate galaxies exhibit greater rotational support than their spheroidal counterparts, but there is significant scatter in the relationship between morphological and kinematical diagnostics, such that kinematically similar galaxies can exhibit a broad range of morphologies. The scatter in the relationship between the flattening and the ratio of the rotation and dispersion velocities (upsilon/sigma) correlates strongly with the anisotropy of the stellar velocity dispersion: at fixed upsilon/sigma, flatter galaxies exhibit greater dispersion in the plane defined by the intermediate and major axes than along the minor axis, indicating that the morphology of simulated galaxies is influenced significantly by the structure of their velocity dispersion. The simulations reveal that this anisotropy correlates with the intrinsic morphology of the galaxy's inner darkmatter halo, i.e. the halo's morphology that emerges in the absence of dissipative baryonic physics. This implies the existence of a causal relationship between the morphologies of galaxies and that of their host dark matter haloes.

KW - galaxies: evolution

KW - galaxies: formation

KW - galaxies: haloes

KW - galaxies: kinematics and dynamics

KW - galaxies: structure

KW - ANGULAR-MOMENTUM EVOLUTION

KW - STAR-FORMATION

KW - INTRINSIC ALIGNMENTS

KW - SAURON PROJECT

KW - STELLAR MASS

KW - BLACK-HOLES

KW - DISC GALAXY

KW - SIMULATIONS

KW - FEEDBACK

KW - SHAPES

U2 - 10.1093/mnras/stz448

DO - 10.1093/mnras/stz448

M3 - Article

VL - 485

SP - 972

EP - 987

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 1

ER -